1. The University of Georgia, GE-0171 Tbilisi, Georgia
2. State Research Center of Russian Federation — Institute for High Energy Physics, NRC “Kurchatov Institute”, 142281 Protvino, Moscow Region, Russia
3. Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN), 108840 Troitsk, Moscow, Russia